Automatic circuit breaker



July 30, 1940. J. SACHS AUTOMATIC CIRCUIT BREAKER Original Filed July 6,1957 3 Sheets-Sheet l In Vent 011:70 s 5 ph Sachs 2; 1/ t July 30, 1940.J. sAcHs 2209,3351

AUTOMATIC CIRCUIT BREAKER Original Filed July 6, 1937 3 SheetsSheet 2Invent 0r: d'asquh Sachs arngy July 30, 1940. J. sAcHs 2,209,351

AUTOMATIC CIRCUIT BREAKER Original Filed July 6, 1937 3 Sheets-Sheet 3F{g.5 5/

I 60 /7/suL,47'/0/v 5 J //VSUL jnr/sntarsdzssjuh 55/3275 Patented July30, 1940 AUTOMATIC cmcurr BREAKER Joseph Sachs, West Hartford, Conn.,assignor to Colts Patent Fire Arms Manufacturing Company, Hartford,Conn., a corporation of necticut Con- Application July s, 1937, SerialNo. 152,020 Renewed October 26, 1939 41 Claims.

The general object of the invention is to provide a circuit breaker ofthe general type disclosed in certain prior patents issued to me, but ofsomewhat simpler construction so that it can be produced at a lowercost.

A more specific object of the invention is to provide a single-breakcircuit breaker having a bodily movable bi-metallic strip ion eifectingautomatic opening and having the said movable strip electricallyconnected through a flexible conductor directly with a stationaryconductor on the base or housing.-

Another specific object of the invention is to provide a circuit breakerhaving a bodily movable bi-metallic strip for eifecting automaticopening and having another conductor in approximately parallelrelationship therewith so that there is obtained not only an electrc-thermal efi'ect but also an electro-magnetic repulsive effect.

' Still another specific object of the invention is to provide improvedmeans for isolating the arcing zone from the mechanical parts of thecircuit breaker and improved means for muilling the arc. Other morespecific objects of the invention are to provide certain improveddetails of structure,

the advantages of which will be, apparentfrom the drawings and thedetailed description.

In the accompanying drawings I have shown four embodiments of theinvention in order that its character may be fully explained, but itwill be understood that the drawings are intended for illustrativepurposes only and are not to be construed .as defining or limiting thescope of the invention, the claims forming a part of this specificationbeing relied upon for that purpose.

Of the drawings:

Fig. 1 is a front view of a circuit breaker embodying the invention,with certain parts broken away to show other parts more clearly.

Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary vertical sectional view similar to Fig. 2, butshowing the parts in the positions which they assume upon automaticopen-' ing while the handle is held in closed circuit position.

Fig. 4 is a'view similar to Fig.3, but showing all of the partsincluding the handle in open circuit positions.

Fig. 5 is a perspective view showing various parts of the circuitbreaker separated from each along the line 12-42 of Fig. 11.

In describing the circuit breaker as shown in Figs. 1 to 6, I will firstdescribe the principal parts of the circuit breaking mechanism,referring only briefly to the associated base or housing. Thereafter thebase or housing will be described in greater detail. The circuitbreaking mechanism is of the same general type as that disclosed in myprior patent for Automatic circuit breaker,

No. 2,020,333 dated November 12, 1935.

A stationary main contact I is provided and also a: stationary conductor2 which is separate from the contact. The contact I and the conductor 2are both mounted upon a suitable base or housing. Directly connectedelectrically with the stationary conductor 2 is a flexible conductor 3.For making and breaking the circuit between the contact I and theconductors 2 and 3 there is provided a movable contact member. As shown,the contact member is movable about a fixed axis,and the said contactmember comprises a conducting element or bar 4 which carries a movablecontact 5 adapted to engage and disengage the stationary contact I.Preferably for a purpose to be set forth, the contact member alsocomprises an arm 6 which is in generally parallel relationship with thebar' 4 and may be constructed as shown in detail in Fig. 5. The arm 6 isformed of sheet metal bent to a U-shape toprovide two similar legs 6, 6and the conducting bar 4 has an angularly bent portion 4 which directlyengages the transverse portion. 6 of. the operating arm, the last saidportions being held together by a rivet.

For supporting the contact member and associated parts there is providedaframe 'lwhich, as shown in Fig. 5, preferably includes two oppositesimilar plates spaced apart and connected with each other by transversemembers 8, 9, i0, and II. The /transverse member 8 is a pivot or bearingmember which extends through holes in the arm li'thus providing apivotal support for .the

50 gages the actuator I! and holds it in its normal entirecontact'member. The bearing member a is supported in insulating bushingsl2, 12 which A handle or operating member 14 is pivotally supported onthe supporting frame I, the transverse member I 0 being utilized asthe-pivotal support. The operating member I4 is biased in the clockwisedirection by a spring l5 In order that the operating member l4 mayoperate the contact 'member, there is provided a connecting mechanismwhich is controlled by means of a bi-metallic element It bodily movablewith the contact member. Preferably and an actuator I! which ismechanically'connected actuator as shown the bi-metallic element Itserves in and of itself as a latch, cooperating directly with with theoperating member.

Preferably and as shown, the actuator I1 is carried directly upon thecontact member so as to move bodily therewith, and the before-mentionedarm 6 is utilized for this purpose. The .actuator i1 is pivotallymounted at It! between the two legs 6, 6 of the operating arm. Theactuatdr is insulated from the arm 6 by means of insulating bushings I8l8 which surround the pivot pin l8 as shown in Fig. 6. These bushingshave shoulders thereon which serve to hold the actuator in centralposition. As shown the H- extends rearward and projects through a slot4' in the conducting arm 6.

A link is is pivotally connected with the operating member H at 2B andwith the actuator H at 2|. With the parts in the normal closedcircuitposition as shown in. Fig. 2, the pivotal am's at 20 is above a.straight line connecting the pivotal axes at l0 and 2|, the operatingmember itself thus co-operating with the link I9 to form a normallylocked toggle. The before-mentioned transverse member 9 engages asuitable shoulder on the handle member to limit movement thereof in thecounter-clockwise direction.

The before-mentioned latch I 6 normally enrelationship with the otherparts as shown in Fig. 2. The bi-metallic latch l6 may be mounted andheld in different ways, but as shown it is provided with an angularly'bent portion it which is'parallel to and in contact with the angularlybent portion 4 of the conducting bar '4. It may be held by the samerivet which connects the conducting bar 4 with the operating arm 6. Thebefore-mentioned flexible conductor 3 is electrically connected with thebi-metallic latch l6 and preferably it is directly engaged therewithnear the upper latching end thereof. This connection may be efl'ected bybrazing.

With the circuit breaker in closed-circuit position as shown in Fig. 2it will be apparent that electrical connection is established from thestationary contact I to the movable contact 5,

thence through the conducting bar 4 and the bi-f metallic latch l6, andthence through the flexible V conductor 3 to the stationary conductor 2.

As already stated, the contact member is biased in the circuit-openingdirection by means of the spring l3, and the operating member is biasedin the clockwise or circuit-opening direc- V and 3 and if an abnormalcur'rift tion by means of the spring l5. However, actual movement in thecircuit-opening direction is normally prevented by reason of thedescribed toggle relationship between the operating mem- I6 isautomatically deflected rearward as indicated in Fig. 3 so as todisengage and release the actuator I I. This deflection ordinarilyoccurs chiefly by reason of the heating of the bi-metallic element.

'When the .actuator is no longer -held by the latch IS, the entirecontact member is moved by the .spring I3 to its, open-circuit positionas shown in Fig. 3, the actuator l1 and the link l9 assuming therelative positions shown in that figure. If the operating member bereleased after the parts have moved to the relative positions shown inFig. 3, the spring 15 moves the operating member to the positionshown inFig. 4, this in turn moving the link l9 and the actuator ll tothepositions shown inthat figure.'

The actuator is thus restored to engaged or engageable relationship withthe bi-metallic latch l6.

The operation has been'described as it occurs when the handle is firstheld and then released. Ordinarily, however theoperating member is notheld and it starts to move to its open-circuit position as soon as theactuator has moved far enough in the clockwise direction to break thelocking relationship between the operating member and thelinklQ. All ofthe parts thus move practically instantaneously to the position shown inFig. 4, the actuator being immediately restored to engaging relationshipwith the latch. As soon as the latch has cooled sufliciently theoperating member can be moved to again close'the circuit.

As already stated, the deflection of the bimetallic latch or strip I 6ordinarily occurs chiefly by reason of the heating thereof by thecurrent. Preferably in order-to augment or accelerate the deflectionupon the attainment of a short circuit or other extreme excess currentconditions, there isprovided a conductor connected in the circuit andlocated closely adjacent the strip and substantially parallel therewith.As shown, this conductor is thelbar 4 which has already been described.In the particular construction shown the bar 4 and the latch l6 areconnected in series and the deflection of the strip is augmented, oraccelerated by the magnetic repulsive efl'ect resulting-from the flow ofcurrent in the closely adjacent and substantially parallel conductors 4and I6.

In order to adjust the bi-metallic latch It for purposes of calibrationit'may be desirable to provide an adjusting screw 22 extending through ahole I6 in the said latch. As shown the operating arm 6 has an extension6 which is positioned to project into a slot 4 formed in the contact bar4. The said extension 6 has a tail portion 6 which enters and flts aslot IS in the latch member thus assisting in holding the latch memberin place. The extension 6 has a threaded hole therein adapted to receivea screw 22. It will be apparent that by adjusting the screw 22 the latchl6 may be moved within certain narrow limits so as to be adapted torelease the actuator upon the attainment of predetermined overloadcondition.

Under some circumstances it may be undesirable or at least unnecessaryto provide an adjustment for the bi-metallic latch. In Fig. 7 aconstruction is shown which is in most respects similar to that shown inFigs. 1 to but which diifers as to the details of the latch mounting. Asshown in this figure the latch 23 is riveted to a latch carrying member24 which is held by the same rivet thatv connects the contact bar 'withthe operating arm. The remainder of the construction is or may beexactly as described and repetition is unnecessary.

The circuit breaker mechanism which has thus far been described may bemounted in various ways and may be used for various purposes. In Figs. 1to 5 there is disclosed one suitable construction for supporting andenclosing the mechanism and there is also disclosed a novel are mufiiingdevice. The supporting and enclosing construction and also the arcmufliing device will now be described in detail, but'it will beunderstood that as to these features I do not necessarily limit myselfto the exact mechanism which has been described. 7

A main base or housing 25 is provided which supports the circuit breakermechanism and all of the conducting parts. As shown this is an integralstructure comprising a rear wall 25 and two forward projecting sidewalls 25, 25 which are spaced apart and which are identical inconstruction. The housing has a front cover 26 which may be of metal,and insulating sheet 21 being interposed between the cover and thehousing. The cover 26, and sheet 21 will be referred collectively asconstituting the front cover plate. The front cover plate is held inplace by screws 28, 28, and it has an opening through which theoperating member l4 projects.

The housing 25 is secured to a metallic supporting plate 29 by means ofthe said screws 26, 28, which thus serve as connection devices forholding the front cover plate and the supporting plate in fixed relationto each other and to the housing. The supporting plate 29 is secured bysuitable means, such as screws 30, 36, to the rear wall. of an outermetallic casing 3|. The casing 3i has an openable front cover 32 securedby screws 33, 33, the said cover preferably having a central depressedportion 32 closely adjacent the housing cover 26. The cover 32 also hasan opening for the operating member l4.

The before-mentioned stationary contact I is carried by a resilientstationary ocnductor 34 located near the-upper end of the base orhousing 25 and held in place by a screw 35. A nut 36 on the screw 35cooperates with the conductor 34 to form a wire terminal. Thebefore-mentioned stationary conductor 2 is secured to the base orhousing 25 near the lower end thereof by means of ,a screw 31. A nut 36on the screw 31 cooperates with the conductor 2 to constitute a wireterminal. I r

The mechanism supporting frame I is positioned between the main sidewalls 25', 25 -of the housing. The frame I is so engaged by the housingthat rearward movement thereof is prevented, and for this purpose theplates of the frame are shown as having lateral projections l 1 whichare seated in notches in the side walls of the housing and which preventrearward movement of the frame. Forward movement of the frame isprevented by the front cover plate 26 when the said plate is in place.Upon removal of the front cover plate the frame and all parts carriedthereby can be freely moved in the forward direction. Such movement islimited by the flexible conductor 3, but complete removal of the frameand of the parts carried thereby is possible when the conductor 2 isdisconnected from the housing.

Extending transversely between the side walls 25' 25 of the housing areinsulating plates and there are preferably three such plates 39, 40, and4|. These plates cooperate with the rear and side walls of the housingto form chambers which are substantially closed except at the front, thefront being substantially closed as before stated by the housing cover26 together with the insulating sheet 21.

The transverse plates 39, 46, and 4| are preferably entered in oppositegrooves formed in the side walls of the housing. The transverse platesengage the rear ends of the grooves so that rearward movement islimited, and the plates are normallyheldagainst forward removal by meansof the housing cover 26.

The circuit breaking mechanism is positioned chiefly in the lowerchamber between the transverse plates 39 and 40. The conducting bar 4projects upward through the transverse plate 40, and as before statedthe operating member I4 projects forward through the covers 26 and 32.The stationary contact I and the movable contact 5 on the conducting bar4 are positioned in the upper chamber between the transverse plates 40and M. Thus the plate 40 serves to separate the arcing zone at thecontacts from the mechanism of the circuit breaker.

Preferably in order that the plate 40 may more eifectively separate thearcing zone from the circuit breaker mechanism, it is made movable andis provided with a relatively small aperture through which the contactbar passes and which it relatively closely fits. The plate is thereforemovable in its own plane and it is so moved whenever the contact bar 4moves to open or close the circuit.

In order that the two chambers may be substantially completely separatedfrom each other, under all conditions, stationary walls are provided inassociation with the movable plate 40. A transverse plate 4i! isprovided at the front, this being positioned in grooves in the sidewalls of the housing and being'held in place by the front cover. Thisplate 40 cooperates with the movable plate 40 to separate the twochambers when the movable plate is in its rearward position as shown inFig. 2. A wall 25 is formed integrally on the rear wall of thehousing,.and this cooperates with the movable plate to separate the twochambers when the movable plate is in its forward position as shown inFigs. 3 and 4.

Preferably an arc mufliing device is positioned in the upper chamberbetween the two plates 40 and 4|, this device being in the main at thefront of the two contacts. Preferably the arc muflling device isaseparate structure normally held in place by the front cover 26, butbeing removable as a unit after the cover has been removed. I

The details of the arc muflling device may be widely varied but as shownit comprises an insulating sheet 42 bent to provide two opposite as anintegral part of the main sheet. The wall 4t has an opening 43 thereinthrough which the contact I projects when the arc muflling device isinplace. 42 42*? are metallic plates 44, 44, oppositely positioned so asto provide a circuitous; or serpentine passageway as clearly shown inFig. 2. Preferably the said walls 42, 42 have slots or apertures.therein in which are seated the end portions of the plates 44, 44. Theentire arc mufliing device is of such size that it substantially fillsthe upper chamber between the plates 40 and 4|. The side walls of thehousing preferably have opposite grooves for the ends of the plates 44,44, as shown in Fig. -1. "The opposite side walls of the arc mufflingdevice have notches 42, 42 therein and the upper wall has a notch 41therein. The side main walls of the housing have notches 25 l5registering "with the notches 42, 42 and the upper plate 4| has a notch4| therein registering with the notch 42. In order to prevent burning ofthat part of the contact bar 4 immediately adjacent the contact 5 thereis preferably provided an insulating element 45. This element has a hole45 therein through which the contact 5 projects and it has ears 45 45thereon which are bent around the bar 4 to hold the insulating elementin place. When the movable contact 5 is moved away from the stationarycontact I, either manually or automatically, any arc-formed gases areforced to move in a generally forward direction through the serpentinepassageway between the plates 44, 44. With the movable plate 40 in itsforward position as shown in Figs. 3 and 4, the gasses can escape onlythrough the notches 42, 42 and 42 Thus the gasses are not only preventedfrom entering the lower chamber which contains bar 68 and the said endof the latch is electricalthe circuit breaker mechanism, but they areguided in a serpentine or circuitous path so as to be cooled prior tobeing discharged from the circuit breaker housing.

is a removable cover 41. A stationary contact 4B is provided which ismounted on a resilient conductor, 49; The conductor 49 is held in placeby a screw 50; and a nut 5| on the screw provides a wire terminal. Astationary conductor 52 is secured to the base or housing by means of ascrew 53. The conductor 52 is in clamping engagement with a flexibleconductor 54 which extends into the interior of the housing. A nut 55 onth screw 53 serves as a wire terminal.

Within the housing 46 is a contact member which includes a conductingelement or bar 56 carrying a movable contact 51 adapted to engage thestationary contact 48. The conducting element or bar 56 is pivotallymounted at or near the end thereof opposite the contact. As

shown, the said element or bar is positioned between two insulatingplates 58, 5B and issecured thereto by means ofrivets. Also positionedbetween the plates 58, 58 and similarly secured thereto is'a conductingplate 59. A' pivot pin 60 Carried by the opposite wallsis mounted insuitable apertures in the side walls of the housing 46 and extendsthrough suitable apertures in the insulating plates 58, 58. In this waythe contact member is pivotally mounted" for movement about the axis ofthe pin 60. It 5 is biased for movement in the contact disengaging orcircuit-opening direction by means of a spring 6!.

A handle or operating-member 62 is pivotally supported on a pin 63extending transversely be- 10 tween the side walls of the housing. Aspring 64 serves to bias the operating member for movement in theclockwise or circuit-opening position.

In order that the operating member may operate the contact member thereis provided a con--15 necting mechanism which is similar in manyrespects to that shown in Figs. 1 to 6. This mechanism includes abi-metallic latch 65 and an actuator 66.

The latch 65 is mechanically connectedto and 20, is movable with theconducting element 56. It is connected near the pivotal axis of theconducting element and it extends in general parallelism therewithtoward the contact carrying end thereof. The latch is also electricallyconnected with 25 a portion of the conducting. element 56 and is alsoelectrically connected with the flexible conductor 54.

As illustrated in the drawings the latch-6.5 has an opening thereinthrough which projects an 30 integral extension 59 on the conductingplate 59, there being an interposed metallic washer'61. The inner end ofthe flexible conductor 54 has electrical connection with the bi-metalliclatch I 65 and preferably it directly engages the latch 35 r at thefront face. thereof and is clamped in place by means of a metallicwasher 61; The forward end of the extension 59 is riveted over as shownto engage the metallic washer 61. 'At the other end of the bi-metalliclatch is a transverse latch ly connected with the conducting bar 56 by'means of a thin flexible conductor 69. This conductor 69 permits thelatch 65 to flex freely under the influence of heat caused by current 5flowing therein.

For supporting the actuator 66 there is provided a U-shaped bracket orarm 16 which is secured at its rear end to the conducting bar 56immediately adjacent the movable contact 51. The said actuator 66 ispivotally mounted at 1| between the two legs of the arm 10. The actuatoris held in central position by means of bushings 1|, 1| which surroundthe pivot pin 11.

Links 12, 12 are pivotally connected with the operating member 62 at 13and with the actuator 65 at 14. With the parts in the normalclosedcircuit position as shown in Fig.8 the pivotal axis at 13 is abovea straight line connecting. the pivotal axes at 63 and 14, the operatingmember itself thus cooperating with the links 12 to form a normallylocked toggle. A transverse pin 15 is provided which serves to limitmovement of the handle member in the counterclockwise direction. 65

With the circuit breaker in closed-circuit position as shown in Fig. 8,it will be apparent that electrical connection is established from thestasame as alreadvdescribed in conjunction with 76 Figs. 1 to 6 anddetailed explanation is unnecessary. The operating member 82 can be usedunder normal circumstances to move the contact member to open or closethe circuit. In the event of an overload the bi-metallic latch isdeflected rearward thus releasing the actuator 88 and permitting boththe contact member and the operating member to move to theiropen-circuit positions.

Another alternative construction is shown in Figs. 11 and 12 and hereagain a simplified base or housing is shown. A main housing 18 isprovided which is closed at the sides and which has a removable cover 18at the front. A stationary contact 18 is provided which is mounted on aresilient conductor 88. The conductor 80 is held in place by a screw 8|and a screw 82 provides a convenient wire terminal.- A stationaryconductor 83 is secured to the base or housing by means of a screw 88. Ascrew 85 serves as a wire terminal. The ends of the housing are closedby insulating plates 88, 88 fitting slots in the side walls, and held inplace by the cover I8.

Within the housing 18 is a movable contact member which comprises twoinsulating plates 81, 81 spaced apart transversely and connected by twotransversely extending conducting elements 88 and 88. These conductingelements extend into suitable slots in the said plates. A movablecontact 80 is carried by the transverse element 88 and is adapted toengage the stationary contact 19. .Rigidly secured to the transverseelement 88 is a bi-metallic latch 8| similar to the latch 85 shown inFig. 8 and similarly provided with a transverse latch bar 82. The latchis electrically connected with the movable contact 88 by a flexibleconductor 88.

There is provided a resilient supporting and conducting element 88having one end rigidly connected mechanically with the conductor 83 andhaving the other end rigidly connected me- .chanically with thetransverseconducting element 88. As shown it is riveted at both ends.

a The said element 84 serves to electrically connect the conductor 83and the latch 8|, and in addition it serves as the sole mechanicalsupport for the corresponding end of the contact member. By reason ofits resiliency the element 83 permits an approximately pivotal movementof the contact member and it biases the said member for movement in thedisengaging or circuit-opening direction. I

A-handle or operating member 85 is pivotally supported on a transversepivot pin 88 extending between the arms of a U-shaped bracket 81. .Thebracket is held in place by a screw 88 and the arms thereof extendforward through slots in the rear wall, of the housing. A spring 88serves to bias the operating member for movement in the clockwise orcircuit-opening position.

In order that the operating member may operate the contact member thereis provided an actuator I88 and two links Nil, Nil. These parts aresimilar in construction and operation to the corresponding parts shownin Fig, 8 and already described in detail. Repetition is unnecessary.

What I claim is:

1. The combination in an automatic circuit breaker, of a stationarycontact, a stationary conductor separate from the said contact, aflexible conductor electrically connected at one end with the stationaryconductor, a movable contact member having a contact adapted to engageand disengage the stationary contact, the said contact member beingbiased for movement toward its open-circuit position and being normallymechanically held against such movement, and a thermostatic bi-metallicstrip supported upon and bodily movable with the contact member andelectrically connected between the movable contact and the other end ofthe, flexible conductor, the said strip being adapted to be heated uponthe attainment of an abnormal current condition therein and thusdeflected so as to mechanically release the contact member and permit itto automatically move to open-circuit position.

2. The combination in an automatic circuit breaker, of a stationarycontact, a stationary conductor separate from the said contact, aflexible conductor electrically connected at one end with the stationaryconductor, a movable contact member including a contact adapted toengage and disengage the stationary contact, the said member beingbiased in the contact disengaging direction, a bodily movablebi-metallic latch on the contact member electrically connected betweenthe movable contact and the other end of the flexible conductor, thesaid latch being 'automatically deflected from its normal relationshipwith the contact member upon the attainment of abnormal currentconditions in the circuit, a movable actuator normally engaged by thelatch to prevent relative movement of the contact member and beingreleased upon automatic deflection of the latch to permit automaticcircuit ible conductor electrically connected at one end with thestationary conductor, a movable contact member including a contactadapted to engage and disengage the stationary contact, the said memberbeing movable about a substantially flxed axis and biased in the contactdisengaging direction, a bodily movable bi-metallic latch on the contactmember electrically connected between the movable contact and the otherend of the flexible conductor, the said latch being automaticallydeflected from its normal relationship with the contact member upon theattainment of abnormal current conditions in the circuit, an actuatorsupported upon and bodily movable w1th the contact member and alsopivotally movable relatively thereto, the actuator being normallyengaged by the latch to prevent relative pivotal movement and beingreleased upon automatic deflection of the latch to permit automaticcircuit-opening movement of the contact member, and means for operatingthe actuator to enable it in cooperation with the latch to normallyeffect the movement of the contact member to and from its contactengaging position.

4. In an automatic circuit breaker, the combination of a stationarycontact, a stationary conductor separate from the said contact, aflexible conductor electrically connected at one end with the stationaryconductor, a movable contact member having a contact adapted to engageand disengage the stationary contact, the said contact member beingbiased for movement toward its open-circuit position and being normallymechanically held against such movement, and a thermostatic bi-metallicstrip rigidly supported at one end upon the contact member and bodilymovable therewith, the, said strip being electrically connected at itsrigidly supported end with the movable contact and at its opposite endwith the other end of the flexible conductor and the said strip beingadapted to be heated upon the attainment of an abnormal currentcondition therein and thus deflected so as to mechanically release thecontact member and permit it to automaticallymove to open-circuitposition.

' 5. In an automatic circuit breaker, the combi- 10 nation of astationary contact, a movable contact member including a conducting barwith a contact thereonadapted to engage and disen gage the stationarycontact, the said member being biased in the contact disengagingdirection, a bodily movable bi-metallic latch on the contact memberclosely adjacent and substantially parallel with the said bar andelectrically connected in the circuit in series therewith, the saidlatch upon the attainment of abnormal ourrent conditions in the circuitbeing automatically deflected from its normal relationship with thecontact member as the result of thermal action within the strip and thesaid latch upon the attainment of extreme excess current conditionsbeing deflected at an accelerated'rate'by reason of magneticrepulsiveaction between the latch and the conducting bar, a pivoted actuatornormally engaged by the latch to-prevent relative pivotal movement andreleased upon automatic g0 deflection of the latch to permit automaticcircuit opening movement of the contact member, and means for operatingthe actuator to enable it incooperation with the latch to normallyeii'ect the movement of the contact member to 35 and from its contactengaging position.

6. .In an automatic circuit'breaker, the combination of ,a stationarycontact, a stationary conductor separate from the said contact, aflexible conductor electrically connectedat one end with the stationaryconductor, a movable conward the contact carrying end thereof, the saidbi-metallic strip being mechanically and electrically connected at theother end with the said flexible conductor so as to be thus included 5in the circuit and the said 'strip upon the attainment of abnormalcurrent conditions in the circuit being automatically deflected from itsnormal relationship with the contact member as the result of thermalaction within the strip and m the said latch upon the attainment ofextreme excess current conditions being'deflected at an accelerated rateby reason of magnetic repulsive action between the latch and theconducting bar, and operating and controlling means adapted for movingthe'c'ontact member to open or close the circuit and adapted forreleasably holding it in clas ed-circuit position, the last said meansbeing ,associated with the bi-metallic element so that upon automaticdeflection oi the element the said 70 means is released to permitautomatic/circuitopening movement of the contact member. I

"7. In an automatic circuit breaker, the combination of astationarycontact, a stationary conductor separate from the said contact, a flex-15 ible conductor electrically connected at one. end

with the stationary conductor, a movable contact member including aconducting bar with a contact thereon adapted to engage and disen-' gagethe stationary contact, the said member being biased in the contactdisengaging direction,

' a bodily movable bi-metallic latch' on the contact member closelyadjacent and substantially parallel with'the said bar and electricallyconnected in seriesv between the said bar and the other end of theflexible conductor, the said flected irom its normal relationship withthe contact member as the result of thermal action within the strip andthe said latch upon the attainment of extreme excess current conditionsbeing deflected at an accelerated rate by reason of magnetic repulsiveaction between the latch and the conducting bar, a pivoted actuatornormally engaged by the latch to prevent relative pivotal movement andreleased upon automatic deflection oi the latch to permit automaticcircuit-opening movement or the contact member, and means for operatingthe actuator to enable .it in cooperation with the latch to normallyeflfect the movement of the contact member to and from its contactengaging position.

8. An automatic circuit breaker comprising in combination, a stationarycontact, a pivoted contact memberincluding an operating, arm and aconducting bar substantially parallel with the arm and having a contactthereon adapted to engage and disengage the stationary contact, the saidmember being biased in the contact disengaging direction, a bodilymovable' bi-metallic latch on the contact member substantially parallelwith the said arm and with the said bar and electrically'connected inthe circuit in series with the bar, the said latch being automaticallydeflected from its normal relationship with the contact member upon theattainment of abnormal current conditions in the circuit, an actuatorsupported upon and bodily movable with the operating arm of the contactmember and also pivotaliy movable relatively thereto, the actupreventrelative pivotal movement and being released upon automatic deflectionof the latch, and means for operating the actuator to enable .it incooperation with the latch'to normally efiect the movement of thecontact member to and from its contact engaging position.

9. An. automatic circuit breaker comprising in combination, a stationarycontact, a pivoted contact member including a conducting element havinga contact thereon adapted to engage and disengage the stationarycontact, the said member being bi in the contact disengaging direction,a bodily movable bi-metallic latch on the contact member at one side ofthe conducting element and electrically connected in the circuit inseries therewith, the said latch being automatically deflected from itsnormal relationflection or the latch, and means for operating ator beingnormally engaged by the latch to the actuator to enable it incooperation with the latch to normally effect the movement of thecontact member to and from its contact engaging position.

10. An automatic circuit breaker comprising in combination, a stationarycontact, a pivoted contact member including an apertured conductingelement having a contact thereon adapted to engage and disengage thestationary contact, the said member being biased in the contactdisengaging direction, a bodily movable bimetallic latch on the contactmember at one side of the conducting element and electrically connectedin the circuit in series therewith, the said latch being automaticallydeflected from its normal relationship with the contact member upon theattainment of abnormal current conditions in the circuit; an actuatorconnected with the contact member for pivotal movement about a movableaxis near the movable contact and at the side of the conducting elementopposite to that at which the latch is positioned, the said actuatorextending through the aperture in the element and being normally engagedby the latch to prevent relative pivotal movement and being releasedupon automatic deflection of the latch, and means for operating theactuator'to enable it in cooperation with the latch to nor,- mallyelfect the movementof the contact member to and from its contactengaging position.

'11. An automatic circuit breaker comprising in combination, astationary contact, a pivoted contact member including an aperturedconducting bar having a contact thereon adapted to engage and disengagethe stationary contact and also including an operating arm at one sideof the conducting bar, the said member being biased in the contactdisengaging direction, a bodily movable bi-metallic latch on the contactmember at the other side of the conducting bar and electricallyconnected in the circuit in series therewith, the said latch beingautomatically deflected from its normal relationship with the contactmember upon the attainment of abnormal current conditions in thecircuit, an actuator supported upon and bodily movable with theoperating arm of the contact member and also pivotally movablerelatively thereto, the actuator extending through the aperture in thebar and being normally engaged by the latch to prevent relative pivotalmovement and being released upon automatic deflection of the latch, andmeans for operating the actuator to enable it in cooperation with thelatch to normally effect the movement of the contact member to and fromits contact engaging position.

12. The combination in an automatic circuit breaker, of a stationarycontact, a contact member including a conducting element pivoted formovement about a fixed axis and also including a contact carrieddirectly by the conducting element near the other end and adapted toengage and disengage the stationary contact to close and open thecircuit, means for biasing the said contact member toward itsopen-circuit position, an actuator carried 'by the conducting elementfor pivotal movement about a transverse axis which is at a substantialdistance from the said fixed axis and in fixed relation to the movablecontact, abodily movable bi-metallic latch me I said latch beingnormally engaged with the actuator but being automatically deflectedfrom its normal relationship upon the attainment of abnormal currentconditions in the circuit 50 as to disengage the actuator and thuspermit automatic movement of the contact member to its open-circuitposition free from restraint by the actuator, and means for operatingthe actuator to enable it in cooperation with the latch to normallyeffect the movement of the contact member to and from its closed-circuitposition.

'13. The combination in an automatic circuit breaker, of a stationarycontact, a contact member including a conducting element pivoted nearone end for movement about a fixed axis and also including a contactcarrieddirectly by the conducting element near the other end and adaptedto engage and disengage the stationary contact to close and open thecircuit, means for biasing the said contact member toward itsopencircuit position, transversely spaced forward extending legs carriedby the conducting element near the contact carrying end thereof, anactuator connected between the said legs for pivotal movement about atransverse axis which is in fixed relation to the movablecontact, abodily movable bi-metallic latch mechanically connected to and movablewith the conducting element and also electrically connected with aportion of the said element, the said latch being normally engaged withthe actuator but being automatically deflected from its normalrelationship upon the attainment of abnormal current conditions in thecircuit so as to disengage the actuator and thus permit automaticmovement of the contact member to its open-circuit position free fromrestraint by the actuator, and means for operating the actuator toenable it in cooperation with the latch to normally effect the movementof the contact member to and from its closedcircuit position.

14. The combination in an automatic circuit breaker, of a stationarycontact, a contact member including a conducting element pivoted nearone end for movement abouta fixed axis and also including a contactcarried directly by the conducting element near the other end andadapted to engage and disengage the stationary contact to close and openthe circuit, means for biasing the said contact member toward itsopencircuit position, an actuator carried by the conducting element forpivotal movement about a transverse axis which is at a substantialdistance from the said fixed axis and in fixed relation to the movablecontact, a bodily movable bi-metallic latch mechanically connected tothe conducting element near the pivotal axis thereof and extending ingeneral parallelism therewith toward the contact carrying end thereof,the said latch being also electrically connected with a portion of thesaid element and the said latch being normally engaged with the actuatorbut being automatically deflected from its normal relationship upon theattainment of abnormal current conditions in the circuit so astodisengage the actuator and thus permit automatic movement of thecontact member to its opencircuit position free from restraint by theactuator, and means for operating the actuator to enable it incooperation with the latch to normally eflect the movement of thecontact memberto and from its closed-circuit position.

15. The combination in an automatic circuit breaker, of a stationarycontact, a stationary conductor separate from the said contact, aflexible conductor electrically connected at one end with the stationaryconductor, a contact member including a conductingelement pivoted nearone end for movement about a fixed axis'and also including a contactcarried directly by the conducting element near the other end andadapted to engage and disengage the stationary contact to close and openthe circuit, means for biasing the said contact member toward its opencircuit position, an actuator carried by the conducting element forpivotal movement about a transverse axis which is at a subtsantialdistance from the said flxed axis and in fixed relation to the movablecontact, a bodily movable bi-metallic latch mechanically connected tothe conducting element near the pivotal axis thereof and'extending-ingeneral parallelism therewith toward conductor and the said latch beingnormally engaged with the actuator but being automatically deflectedfrom its normal relationship upon the attainment of abnormal currentconditions in the circuit so as to disengage the actuator and thuspermit automatic movement of the contact with the conducting, bar andalso pivotally" movable relatively thereto about an axis spaced from thebar, a bodily movable bi-metallic latch on the contact memberelectrically connected with the bar and positionedwith its plane betweenthe bar and the axis of the actuator; the said latch beingnormallyengaged with the actuator but being automatically deflected from itsnormal relationship so as to disengage the actuator upon the attainment.of abnormal current conditions inthe circuit, and means for operatingthe actuator to enable it in cooperation with the latch to normallyeflect the movement of the contact member to and from its contactengaging position.

17. In an automatic circuit breaker, the combination of a stationarycontact, a pivoted contact member including a conducting bar with acontact thereon adapted to engage and disengage the stationary contact,the said member being biased in the contact disengaging direction, aflexible conductor electrically connected with the conducting bar, anactuator supported upon and bodily movable with the conducting bar andalso pivotally movable relatively thereto about an axis spaced from thebar, a bodily movof the contact member to and from its contactengagingposition.

l8. In an automatic circuit breaker, the combination of a base, astationary contact on the base, a stationary conductor on the base separate from the said contact, a movable contact .member having a contactadapted toengage and disengage the stationary contact, the said contactmember being biased for movement toward its open-circuit position andbeing normally mechanically held against such movement, aresilientsupporting and conducting ele-' ment having one end rigidly connectedmechanically with the'base and-having, theother end rigidly connectedmechanically with the contact member smas to serve as a support for thecontact member while permitting the said member to move substantiallypivotally, the said ele-' ment at its first said end being electricallyconnected with the said stationary conductor on the base, and a bodilymovable bi-metallic strip on the contact member electrically connectedin the circuit in series with the said resilient conducting element, thesaid strip being adapted to be heated upon the attainment of an abnormalcurrent condition therein and thus deflected so as to mechanicallyrelease the contact'member and permit it to automatically move toopencircuit position. 4

19. In an automatic circuit breaker, the combination of a base, astationary contact on the base, a stationary conductor on the baseseparate fromthe' said contact, a movable contact member having acontact adapted to engage and disengage the stationary contact, the saidcontact member being biased for movement toward its open-circuitposition and being nor-" mally mechanically .held against such movement,a resilient supporting and conducting ele- I move substantiallypivotally, the said element at its flrst said end'being electricallyconnected with a bodily movable bi-metallic strip on the contactmemberelectrically connected in series bethe said movable contact, the saidstrip being adapted to be heated upon'the attainment of an abnormalcurrent condition 'therein and thus deflected so as to mechanicallyrelease the contact member and permit it to automatically move toopen-circuit'position.

20. The"combination in an automatic circuit breaker, of a base, astationary contact on the base, a stationary conductor on the baseseparate from the said contact, a movable contact memthe said stationaryconductor on the base, and

- tween the said resilient conducting element and her including acontact adapted to engage anddisengage the stationary contact, aresilient supsaid member to move substantially pivotally, the

said element" at its first said end being ,electzically connected/withthe said stationary conducl V tor onthe base, a bodily movablebi-metallic latch on the contact member electrically con- :nected inseries between the said resilient conducting element and the saidmovable contact, the said latch being automatically deflected from itsnormal relationship with the contact member upon the attainment ofabnormal current conditions in the circuit, and an actuator normallyengaged by the latch to effect the movement of the contact member to andfrom its contact engaging position, the said actuator being disengagedby the latch upon automatic deflection of the latter to permit automaticcircuit-opening movement of the contact member.

forward direction, and an automatic breaking mechanism carried by thefram and freely movable in the forward direction when the frame is somoved, the said mechanism being positioned chiefly within the housingchamber and having a movable handle at the front extending through theopening in the front plate.

22. In an automatic circuit breaker, the combination ofa housing formedwith a rear wall and with parallel side walls spaced apart, a platesubstantially closing the housing at the 'front but having a handleopening therein, the

entire rear face of the said plate being flat and the saidrear facebeing in engagement with the front .edges of the housing side walls, ,amechanism supporting frame positioned entirely be tween the housing sidewalls and engaged by the housing to prevent rearward movement, the saidframe being behind and in engagement with the said flat rear face of thefront plate and the said frame being held by the plate and beingotherwise freely movable in the forward direction, two conducting meansadjacent the respective end portions of the housing and supportedindependently of the frame, and an automatic circuit breaking mechanismcarried by the frame and freely movable in the forward direction whenthe frame is so moved. the said mechfaces, two insulating platesextending transversely between the side walls and positioned in the saidopposed grooves, a mechanism supporting frame positioned between theside walls and engaged by the housing to prevent rearward movement, acover plate substantially closing the housing at the front but having ahandle opening therein, the/said cover beingimfront of the saidtransverse plates and in front of the frame and preventing removalthereof, two conducting means carried by the respective end portions ofthe housing at the outer sides of the said transverse plates,'and anautomatic circuit breaking mechanism carried by the frame and positionedat least chiefly between the transverse plates and serving when inclosed-circuit position to electrically connect the said two conductingmeans on the end portions of the housing, the said mechanism having amovable handle at the front extending through the opening in the frontcover.

24. In an automatic circuit breaker, the com= bination of a housingformed with a mechanism containing chamber open at the front, a coverplate substantially closing the housing chamber at the front but havinga handle opening therein, a mechanism supporting frame positionedentirely within the housing chamber and engaged by the housing toprevent rearward movement, the said frame being behind and in engagementwith the front cover plate and the said frame held by the plate andbeing otherwise free- 1y movable in the forward direction, arr automaticcircuit breaking mechanism carried by the frame and freely movable inthe forward direction when the frame is so moved, the said mechanismbeing positioned chiefly within the hous= ing chamber and having amovable handle at the front extending through the opening in the frontcover plate, a supporting plate in engage= ment .with the housing at therear thereof, con-= nection devices extending from the front cover plateto the rear supporting plate and serving to hold the said plates infixed relation to each other and to the housing, and means on the rearsupporting plate whereby it may be independently secured to a stationaryrear wall.

25. In an automatic circuit breaker, the combination of an insulatinghousing provided with parallel side walls spaced apart, an aperturedinsulating partition plate extending transversely between the side wallsand movable in its own plane, a stationary contact at one side of themovable plate, and an automatic circuit breaking mechanism positionedbetween the side walls of the housing ,and chiefly at the other side ofthe movable plate, the said mechanism including a movable-contact barextending through and approximately fitting the aperture in the movableplate and having a contact thereon adapted to engage and disengage thestationary contact.

26. In an automatic circuit breaker, the combination of an insulatinghousing provided with walls substantially enclosing all but one side ofa contact containing chamber, an apertured plate subtsantially closingthe remaining side of the said chamber and rectilinearly movable in itsown plane, a stationary contact within the saidchamber and at one sideof the movable plate, and an automatic circuitbreaking mechanismpositioned chiefly at the other side of the iii movable plate andoutside of the said chamber,

the said mechanism including a movable contact bar extending through andapproximately fitting the aperture in the movable plate and having acontactsthereon within the chamber adapted to engage and disengage thestationary contact.

27. In an automatic circuit breaker, the combination of an insulatinghousing provided with parallel side walls spaced apart and having a pairof opposed grooves in their inner faces, an

. apertured insulating partition plate extending transversely betweenthe side walls and movable in the said opposed grooves, a stationarycontact at one side of the movable plate, and an automatic circuitbreaking mechanism positioned between the side walls of the housing andchiefly at the other side of the movable plate, the

mechanism including a movable contact bar extending through andapproximately fitting the aperture in the movable plate and having acontact thereon adapted to engage and disengage the stationary contact.

28. In an automatic circuit breaker, the combination of an insulatinghousing provided with parallel side walls spaced apart and having twopairs of closely spaced opposed grooves in their inner faces, anapertured insulating plate extending transversely between the side wallsand movable in the grooves of one pair, a stationary plate in thegrooves of the other pair and cooperating with the movable plate to forma partition which is substantially closed with the movable plate in anyposition, a stationary contact at one side of the movable plate; and anautomatic circuit breaking mechanism positioned between the side wallsof the housing and chiefly at the other side of the movable plate, thesaid mechanism including a movable contact bar extending through andapproximately fitting the aperture in the movable plate and having acontact thereon adapted to engage and disengage the stationary contact,

29. In an automatic circuit breaker, the combination of an insulatinghousing provided with parallel side walls spaced apart and having a pairof opposed grooves in their inner faces, two

insulating plates extending transversely between the sidewalls and withone of them apertured and movable in the said opposed grooves, astationary contact at the outer side of the movable.

, plate, and an automatic circuit breaking mechanism positioned betweenthe side walls of the housing and chiefly between the two transverseplates, the said mechanism including a movable contact bar extendingthrough and approximately fitting the aperture in the movable plate andhaving a contact thereon adapted to engage and disengage the stationarycontact.

30. In an automatic circuit breaker, the combination of an insulatinghousing provided with parallel side walls spaced apart and having twopairs of opposed grooves in their inner faces, two insulating platesextending transversely between the side walls and positioned in the:said

/ opposed grooves, one of the said plates being apertured and movable inits grooves, a cover substantially closing the casing at the front buthaving a handle opening therein, the said cover being in front of thesaid transverse plates and preventing'removal thereof, a stationarycontact at the outer side of the movable plate, and an automatic circuitbreaking mechanism positioned between the side walls of the housing andchiefly between the two transverse plates, the said mechanism includinga movable contact bar extending through and approximately fitting theaperture in the movable plate and having a contact thereon adapted toengage and disengage the stationary contact, the said mechanism having amovable handle at the front extending through the opening in the frontcover.

31. The combination in an automatic circui the said chambers, astationary contact in one of the said enclosed chambers and electricallyconnected with one of the said conducting means, and an automaticcircuit breaking mechanism positioned chiefly in the other enclosedchamher and electrically connected with the other of the said conductingmeans, the said mechanism.

including a movable contact bar extending into the chamber containingthe stationary contact and having a contact thereon adapted to engageand disengage the said stationary contact and the said mechanism havinga movable handle at the front extending through the opening in the frontcover.

32. The combination in an automatic circuit breaker, of an insulatinghousing provided with parallel side walls spaced apart and' having threepairs of opposed grooves in their inner faces, a cover substantiallyclosing the housing at the front but having a handle opening therein,three insulating plates extending transversely between the side wallsand positioned in the said opposed grooves and providing twosubstantially enclosed chambers, the inner one of the said three platesbeing apertured and movable in its grooves, two conducting means carriedby the respective end portions of the housing outside of the saidchambers, a stationary contact in one of the said enclosed chambers andelectrically connected with one of the said conducting means, and anautomatic circuit breaking mechanism positioned chiefly in the otherenclosed chamber and electrically connected with the other of the saidconducting means, the said mechanism including a movable contact barextending through and approximately fitting the aperture in the movableplate and having a contact thereon in the contact containing chamberadapted to engage and disengage the stationary contact and the saidmechanism having a movable handle at the front movable front cover meansnormally substantially closing both of the chambers at the front, astationary contact in one of the said chambers, an automatic circuitbreaking mechanism positioned chiefly in the other chamber and includinga movable contact bar extending into the chamber containing thestationary contact and having a contact thereon adapted to engage anddisengage the stationary contact, and an arc mufiiing device in thechamber containing the contacts and in front of the said contacts.

34.,An automatic circuit breaker comprising in combination, aninsulating housing provided with two closely adjacent chambers separatedby a relatively thin partition, the said chambers being substantiallyclosed except at the front, re-

1 movable front cover means normally substantially closing'both of thechambers at the front, a stationary contact in one of the said chambers,an automatic circuit breaking mechanism positioned chiefly in the otherchamber and including a movable contact bar extending into the chambercontaining the stationary contact and having a contact thereon adaptedto engage and disengage the stationary contact, the said me'ch anismbeing readily movable from its chamber as a unit in the forwarddirection upon removal of the front cover means, and an arc mufllingdevice in the chamber containing the contacts and in front of the saidcontacts.

35. An automatic circuit breaker comprising in combination, aninsulating housing provided with two closely adjacent chambers separatedby a relatively thin partition, the said chambers being substantiallyclosed except at the front, removable front cover means normallysubstantially closing both of the chambers at the front, a stationarycontact in one of the said chambers, an automatic circuit breakingmechanism positioned chiefly in the other chamber and including amovable contact bar extending into the chamber containing the stationarycontact and having a contact thereon adapted to engage and disengage thestationary contact, the said mechanism being readily movable from itschamber as a unit in the forward direction upon removal of the frontcover means, and an arc mufliing device in the chamber containing thecontacts and in front of the said contacts, the said are muiiling devicebeing readily movable from its chamber as a unit upon removal of thefront cover means.

36. An automatic circuit breaker comprising in combination, aninsulating housing formed with a rear wall and with parallel side wallsspaced apart, the said side walls having two pairs of opposed grooves intheir inner faces, two insulating' plates extending transversely betweenthe side walls and positioned in the said opposed grooves to provide achamber which is substantially closed except at the front, a coversubstantially closing the chamber at the front and positioned in frontof the said transverse plates to prevent removal thereof, a stationarycontact in the said chamber, an automatic circuit breaking mechanismpositioned chiefly outside of the said chamber adjacent one of thetransverse plates, the said mechanism including a movable contact barextending into the chamber and having a contact thereon adapted toengage and disengage the stationary contact, and an arc muffling devicein the chamber in front of the said contacts, the said muming devicebeing normally held in place by the front cover but being readilyremovable as a unit in the forward direction upon removal of the cover.

37. An automatic circuit breaker comprising in combination, aninsulating housing formed with a rear wall and with parallel side wallsspaced apart, the said side walls having three pairs of opposed groovesin their inner faces, three insulating plates extending transverselybetween the side walls and positioned in the said opposed grooves toprovide two chambers which are substantially closed except at the front,a cover substantially closing the chambers at the front and positionedin front of the said transverse plates to prevent removal thereof, astationary contact in one chamber, a mechanism supporting framepositioned in the other chamber and having lateral projections engagingthe side walls to prevent rearward movement, the said frame being heldin place by the cover but otherwise readily movable in the forwarddirection, an automatic circuit breaking mechanism carried by the frameand positioned at least chiefly in the'same chamber, the said mechanismincluding a movable contact bar extending into the chamber containingthe stationary contact and having a Contact thereon adapted to engageand disengage the said stationary contact, and an arc mufliing device inthe chamber containing the contacts and in front of the said contacts,the said muffling device being normally held in place by the front coverbut being readily movable as a unit in the forward direction uponremoval of the cover.

38. For an automatic circuit breaker, an arc opposite parallel sidewalls, an end wall, and a plurality of transverse substantially parallelplates extending between the said walls and spaced apart longitudinally,alternate plates being respectively closely adjacent and spaced from theend wall so as to provide a circuitous passageway through the mufller.

39. For an automatic circuit breaker, an arc muifling device comprisingin combination an insulating sheet bent to provide two opposite parallelwalls, the said walls having pairs of opposite apertures therein spacedapart longitudinally, and transverse plates having end projectionsseated in the said apertures, the said plates being in staggeredrelationship so as to provide a serpentine passageway through themufller.

40. In an automatic circuit breaker, the combination of an insulatinghousing provided with a chamber open at the front but otherwisesubstantially closed, a removable front cover normally substantiallyclosing the chamber at the front, a stationary contact in the chamber,an automatic circuit breaking mechanism positioned chiefly outside ofthe chamber and including a movable contact bar extending into thechamber and having a contact thereon adapted to engage and disengage thestationary contact, and an arc muflling device in the chamber in frontof the said contacts, the said muiiling device comprising transverseplates providing a circuitous passageway for arc formed gases.

41. In an automatic circuit breaker, the combination of an insulatinghousing provided with a chamber open at the front but otherwisesubstantially closed, a removable front cover normally substantiallyclosing the chamber at the front, a stationary contact in the chamber,an automatic circuit breaking mechanism positioned chiefly outside ofthe chamber and including a movable contact bar extending into thechamber and having a contact thereon adapted to engage and disengage thestationary contact, an insulating sheet positioned in the chamber infront of the said contacts and bent to provide two opposite parallelwalls, the said walls having pairs of opposite apertures therein spacedapart longitudinally, and transverse plates having end proiectionsseated in the said apertures, the said plates being in staggeredrelationship so as to provide a serpentine passageway for are formedases.

. muifling device comprising in combination two Josngn SACHS.

